It is the purpose of these technical and clinical studies to further advance the non-invasive evaluation of infants with congenital heart disease by providing specialized high-frequency phased array devices at 7.5 MHz and 10 MHz and specifically designed pediatric endoscopic devices for intraoperative exploration of congenital heart anatomy and for three- dimensional reconstruction of complex cardiovascular malformations. Our previous work on the first two years of this proposal has resulted in the design and implementation of the first functional 7.5 MHz miniaturized 64 element pediatric probes and their application in pediatric heart, abdominal, intracranial imaging and the imaging of vascular anatomy enhanced by Doppler and color flow methods. The probes served as the impetus for the development of commercial 7.5 MHz probes both by General Electric and attempts by other companies to master this technology. (Two probes at 7.5 MHz have been prepared by other groups. None is near-field optimized or is as high in resolution as ours). Further optimization of the design parameters of 7.5 MHz probes and the development of 10 MHz phase array probes should further advance pediatric cardiovascular imaging. Additionally, the rapid evolution of endoscopic and esophageal methods for evaluating patients' heart disease has proven of substantial importance in adult cardiology. In pediatric cardiology because of the complexity of congenital disease anatomy, there is also crucial need for miniaturized devices for use in babies for intraoperative monitoring of congenital heart disease repair. No high frequency pediatric endoscopes exist suitable for newborn infants. The endoscopic devices that we proposed to develop and build includes 7.5 MHz and 10 MHz endoscopic probes with 6 to 8 mm2 phased array tips built on 6 mm pediatric esophagoscopes which will be capable of multi-planar imaging and three dimensional reconstruction of cardiac structure and flow. Our efforts in extending the range and versatility of phased array devices in the 7.5 to 10 MHz frequency range and developing endoscopic multi-planar 3-dimensional imaging methods should yield major advances in diagnostic and surgical planning for pediatric heart patients.